Current techniques for the preservation of fresh post-harvest produce include temperature and/or pressure treatment, controlled atmosphere packaging, wax and similar coating techniques, synthetic polymer coating techniques, polymer packaging and genetic engineering of various metabolic pathways that cause ripening.
Various coating compositions have been proposed, e.g., a petroleum solvent solution of a waxy film former and a fungicide (U.S. Pat. No. 4,006,259); a mixture of lard, tallow, and lecithin applied in molten state (U.S. Pat. No. 4,207,347); hydrogenated jojoba oil U.S. Pat. No. 4,356,197); a salt of carboxylic acid and an alkyl amine (U.S. Pat. No. 4,532,156); a 3% oil-in-water emulsion of hydrogenated vegetable oil, stearic acid, and anionic emulsifier, (U.S. Pat. No. 4,649,057); the combination of a food acid, and edible reducing agent and a carbohydrate thickener followed by freezing (U.S. Pat. No. 4,751,091); a denatured proteinaceous solution of soybeans, wheat and corn (U.S. Pat. No. 5,128,159); simultaneously scrubbing and drenching with a liquid containing fungicide (U.S. Pat. No. 5,148,738); a slurry consisting of by products of the produce and certain sugars and acids (U.S. Pat. No. 5,364,648); a mixture of a polysaccharide polymer, a preservative, an acidulent and emulsifiers (U.S. Pat. Nos. 5,198,254 and 5,376,391); and, a light activated composition (U.S. Pat. No. 5,489,442).
Various forms of produce packaging are disclosed, by the way of example, in U.S. Pat. Nos. 4,769,262; 5,030,510; 5,093,080; 5,160,768; 5,427,807; 5,547,693; and 5,575,418.
Some Russian and Japanese publications have proposed the use of polyvinyl alcohol as a gas barrier coating for produce, but few if any of these suggestions have found their way into the commercial market.
U.S. Pat. Nos. 6,165,529 and 6,203,833 commonly owned by the assignee of this application, disclose highly improved processes for preserving fresh produce and coating compositions therefore comprised of substantially hydrolyzed cold water soluble polyvinyl alcohol, low molecular weight cold water soluble starch, and surfactant. Optional additional ingredients are plasticizer, antimicrobrials, and antifoaming agents, preferably the starch is maltodextrin, the surfactant lecithin or dioctyl sodium sulfosuccinate, the antimicrobrials methylparaben, and the plasticizer glycerin.